This invention relates to a film obtained from a heat resisting silsesquioxane polymer and a cured film thereof. The present invention is also directed to a method of preparing the film. The present invention is further directed to a composite material having the above film or cured film.
The present inventors disclose in Japanese patents Nos. 2,884,073, 2884074 and 3,020,164 a hydrosilylated polymer obtained by reacting octakis(hydridosilsesquioxane), namely pentacyclo-[9.5.1.13,9.15,15.17,13]-ocatasiloxane, which is one of a cage-type hydridosilsesquioxanes, with a monoyne or diyne compound. In the hydrosilylated polymer, part of the hydrogen atoms bonded to the silicon atoms thereof may be substituted by an alkyl group or an aralkyl group. This polymer, which is soluble in organic solvents, is highly thermally stable. Japanese patent No. 2,884,073 also disclose the formation of a film by applying an organic solution of the hydrosilylated polymer to a glass substrate. The coating is dried at room temperature in a nitrogen gas flow and then in vacuum. The resulting film, however, has been found to form cracks and is relatively easily delaminated from the substrate.
It is, therefore, an object of the present invention to provide a film of a hydrosilylated polymer which is free of defects such as cracks and which can be tightly adhered to a substrate.
Another object of the present invention is to provide a film of the above-mentioned type which does not absorb moisture and which has high water resistance, high resistance to chemicals, good weatherability, good electric insulation properties and high mechanical strengths.
In accordance with one aspect of the present invention, there is provided a film obtained by heating a coating of a resin composition at a temperature lower than 300xc2x0 C. but not lower than 40xc2x0 C. in air or in an inert atmosphere, said resin composition comprising a hydrosilylated polymer obtained by reacting at least one hydridosilsesquioxane compound of the following formula (1):
(HSiO3/2)nxe2x80x83xe2x80x83(1) 
wherein n is an integer of 4-1000, with at least one compound of the following formula (2)
R1xe2x80x94Cxe2x89xa1Cxe2x80x94R2xe2x80x83xe2x80x83(2) 
wherein R1 represents a hydrogen atom, a monovalent organic group or a monovalent organosilicon group and R2 represents a hydrogen atom or a group of the formula:
xe2x80x94(Rxe2x80x2)qxe2x80x94Cxe2x89xa1Cxe2x80x94R 
where Rxe2x80x2 represents a divalent organic group or a divalent organometallic group, R represents a monovalent organic group or a monovalent organosilicon group and q is 0 or 1
with the proviso that when R1 is a hydrogen atom R2 is a hydrogen atom.
In another aspect, the present invention provides a method of preparing a film, comprising applying a coating of a composition to a substrate, and heating said coating at a temperature lower than 300xc2x0 C. but not lower than 40xc2x0 C. in air or in an inert atmosphere for a period of time sufficient to form a film on said substrate, said composition comprising a hydrosilylated polymer obtained by reacting at least one hydridosilsesquioxane compound of the following formula (1):
(HSiO3/2)nxe2x80x83xe2x80x83(1) 
wherein n is an integer of 4-1000, with at least one compound of the following formula (2)
R1xe2x80x94Cxe2x89xa1Cxe2x80x94R2xe2x80x83xe2x80x83(2) 
wherein R1 represents a hydrogen atom, a monovalent organic group or a monovalent organosilicon group and R2 represents a hydrogen atom or a group of the formula:
xe2x80x94(Rxe2x80x2)qxe2x80x94Cxe2x89xa1Cxe2x80x94R 
where Rxe2x80x2 represents a divalent organic group or a divalent organometallic group, R represents a monovalent organic group or a monovalent organosilicon group and q is 0 or 1
with the proviso that when R1 is a hydrogen atom R2 is a hydrogen atom.
The present invention also provides a cured film obtained by heating the above film at a temperature of 300-1500xc2x0 C. in an inert atmosphere.
The present invention further provides a method of preparing a cured film, comprising heating the above film at a temperature of 300-1500xc2x0 C. in an inert atmosphere for a period of at least 1 minute.
The present invention further provides a composite material comprising a substrate, and the above film or cured film provided on said substrate.
The present invention further provides a semiconductor device having the above film or cured film.
The above film or cured film according to the present invention is suitably used for various applications such as a protecting film (e.g. a passivation film of a semiconductor), a barrier coat film, a resist film, an insulation film (e.g. an interlayer insulation film of a semiconductor) and a heat resisting film.